Worried! How to care for likely overwatered Phalaenopsis?

[HiOrcDen]

I think I've overwatered one of my phals. It's a plant with small, succulent dark purple flowers, which my grower calls "chocolate drops". Of the roots visible through the plastic pot, over half appear grey and soft. The plant has dropped about ten blooms of about fifty blooms, as well as buds and spikes which are neither dropping nor opening. What has me particularly worried is that one bottom leaf is starting to take on a yellow tinge.

My question is, how should I help this orchid recover? I am thinking I should water lightly and allow it to dry between watering. Is there anything in addition I should do? For example, should I pull it from its pot and trim away the dead roots, to keep rot from spreading? Should I continue to provide the same light levels?

Any guidance would be greatly appreciated!